The present invention relates to a display driver and a display device, and particularly to a circuit which can be suitably used for driving gate lines of an active matrix type display panel.
In regard to display devices including liquid crystal display (LCD: Liquid Crystal Display) device, the upsizing of display panels, and the rise in definition to a higher level are proceeding. In many cases, active matrix type display panels are adopted for such display devices. An active matrix type display panel has source lines and gate lines which are arranged to intersect with one another; one pixel is disposed at each intersection. Electric charges corresponding to display data are transmitted from the source lines to the pixels selected by the activated gate lines; the brightness to be displayed by each of the pixels depends on the charge transmitted to the pixel. With the upsizing of display panels and the rise in definition to a higher level, the problem of the unevenness such as the inclination of brightness to be displayed in a display plane come to the surface.
The Japanese Unexamined Patent Application Publication No. JP-A-2005-345752 has disclosed an image display device which compensates a drop in voltage arising on the internal resistance of a switch inside a scan line (gate line) control circuit to reduce the drop in brightness. JP-A-2008-77005 and JP-A-2009-163255 each have disclosed a display driver which corrects the difference in voltage drop in each row of gradation signals output by a source driver by changing a scan signal voltage to be applied to a scan line (gate line) involved by the row. JP-A-2012-88550 has disclosed an image display device which can suppress the unevenness of brightness stemming from line resistances and line capacitances of vertical lines (source lines). If a horizontal line (gate line) is selected and activated, in synchronization with this, the resistance between a vertical line and its drive circuit is changed according to the position of the selected horizontal line.
The inventor examined the following patent documents prior to the invention hereof: JP-A-2005-345752; JP-A-2008-77005; JP-A-2009-163255; and JP-A-2012-88550.